Method of fire polishing glassware



May 9, 1950 c. A. BORCHERT ETAL 1 2,507,433

METHOD OF FIRE POLISHING GLASSWARE Filed July 14, 1943 INVENTORSClarehcfi Ajiorchert Rabert H. Johnson J? 4 WWW %QRNEY Patented May 9,1950 METHOD OF FIRE POLISHING GLASSWARE Clarence A. Borchert and RobertH. Johnson, Weston, W. Va.; said Johnson assignor to said BorchertApplication July 14, 1943, Serial No. 494,670

7 Claims- This invention relates generally to the glass industry and isparticularly directed to improve ments in the manufacture andornamentation of cut glass tableware.

An object of this invention resides in the provision of a method offinishing glassware by which mass production of fine, plain or richlyornamented ware are attained at relatively low cost.

A further object is the provision of a method by which fine cutglassware can 'be fire polish-ed quickly and easily while maintainingthe definition of the design.

A still further object is to produce polished cut glassware having afiner finish whether composed of low or high grade of glass.

Another object is the provision of a method of fire polishing vitreousmaterial in which the material is preheated to a uniform temperaturethroughout and then subjected to special heat treatments to producetemperature differentials between opposite surfaces of the material inthe same region, the higher temperature being sufficient to fuse thematerial but being applied for such a short time period as to fuse thematerial at the surface only whereby the article will retain itsstability, the treatments being repeated as many times as necessary toproduce the desired finish.

- Another object also resides in the provision of a method of finishingglassware in which the articles are preheated, then placed on aturntable and revolved while a concentrated source of heat is applied toa wall thereof to fuse the material at the immediate surface, therotation of the turntable and the application of lower temperature fluidto the opposite side of the wall, serving to prevent the major part ofthe material behind the fused portion from reaching a temperaturewherein its stability will be lessened.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of embodiment of the invention isclearly shown.

In the drawings:

Fig. 1 is a diagrammatic view of a combined heating and cooling lehr orkiln having an endless conveyor extending therethrough, the lehr or kilnbeing used in carrying out the method forming the subject matter of thisinvention:

Fig. 2 is a perspective view of a turntable employed in performing oneof the steps in the method; 'Fig. 3 is a fragmentary horizontalsectional 2 view taken through an article during the polishing operationand,

Fig. 4 is a detailed view partly in section, showing the operation ofcutting a design in a glass article, the thickness of the wall of thelatter being exaggerated to facilitate illustration.

The glassware A to be ornamented by the process set forth herein isusually of the thin walled type which cannot be exposed to high heat forsustained periods without destruction. It is first treated to producethe desired design in intaglio in the usual manner by exposing theselected area to the action of a cutting wheel B as illustrated in Fig.4. This stepin the method can be performed by hand by a skilled workmanor in any other suitable manner. After the articles have had the designcut therein, they are then fire polished in accordance with the presentinvention.

In carrying out the present invention, use is made of a tunnel lehr orkiln 20 of the type illustrated in Fig. 1 and which comprises anelongated enclosure 2| having a heatin section 22 and a cooling section23. Between these sections, the side wall of the enclosure is providedwith an opening 24 through which access may be had to the interiorthereof. It will be noticed from Fig. 1 that'the heating section is ofshort length when compared to the cooling section, since less time willbe consumed in raising the temperature of ware introduced into the kilnthan will be required to cool the same after treatment. Each end of theenclosure is open to permit an endless conveyor 25 to extend completelythrough the enclosure, that is, from one end to the other. Any suitablemeans may be :provided to impart longitudinal movement to the conveyor,the upper strand thereof moving through the enclosure in the directionindicated by the arrow.

The section 22 of the kiln has a plurality of burners 26 directedthereintoto raise the temperature within this section. Gas is preferablyused as a fuel because of its clean burnin characteristic and theconvenience in operation and control The front or inlet end of theenclosure is provided with a stack 21 through which the waste gas may beexhausted, these gases traveling counter-current to the movement of theware, being treated, through the enclosure.

' The speed of the conveyor is adjusted and the heat is applied so as togradually raise the temperature of the ware during its travel throughthe heating section to'iapproxlmately 1.000 F; When this ware reachesthe opening 24, it is removed and fire polished by applying anextraneous source or sources of heat to the ware by rotating the wareand directing the source or sources of heat thereagainst by hand or inany other suitable manner. In the present embodiment, the ware, afterbeing removed from the lehr, is placed on a turntable 28 with an axis ofthe ware in alignment with the axis of rotation of the turntable. Theturntable is disposed adjacent the opening 2E. The turntable is thenrevolved at a predetermined rate of speed through any suitable meanssuch as an electric motor 29 and a belt arrangement shown at 39, whilethe polishing operation is performed. The rate of rotation of the warewill depend upon the size thereof, larger articles being rotated at alower rate than the smaller articles due to the fact that as the surfacebeing operated upon is farther from the axis of rotation, its linearspeed will be greater than the linear speed of the surface of a smallerarticle turning at the same rate.

While the ware is undergoing the rotation, its temperature is maintainedat approximately 1,000" F. by directing a secondary flame thereagainst,this flame issuing from a burner 3! provided for this purpose. In theevent the articles being polished are of unusual size, it is within theconcept of the invention to employ as many burners as are necessary tokeep the articles at the desired temperature. These secondary burnersare so positioned with respect to the ware that the desired temperaturewill be maintained and yet the ware will not be permitted to overheat.

In addition to the secondary burner or burners, a source or sources ofhigh temperature heat is directed against the surface of the ware to bepolished. In the present embodiment, a small diameter burner, burners ora torch or torches 32 are utilized. Highly satisfactory results havebeen obtained through the use of a burner with a number nine tip, theoutlet of which is approximately one thirty-secondth of an inch indiameter. It will be understood that the tip employed will depend on thethickness of the ware; a larger diameter tip will be used when thickware is to .be polished and another diameter tip when thin ware is to bepolished. In performing the polishing operation, the torch or torches 32are held in closely adjacent relationship to the surface of the articlebeing operated .on, in order to confine the flame or flames to a smallarea. Due to the high temperature of the flame and the speed of rotationof the article, the flame will be applied to the surface for a length oftime surficient to fuse only the material at the surface in the areacontacted by the flame. As soon as the surface leaves the flame, due tothe rotation of the ware, the temperature of the surface will fall andthe fused portion will solidify substantially immediately. It has beenfound that the fusing takes place to a depth less than .001 of an inchand even though the surface has beencut to produce sharp-designs, thesewill not be obliterated or changed in any way. In the polishing operation, the flame from the torch 32 is usually repeatedly applied to anyone area until the desired result is obtained. When the entire outersurface of an article, such as the goblet illustrated, is to bepolished. the torch :32 is held in closely adjacent relation ,to thearticle and preferably stationary and as the latter revolves, therepeated surface fusing will gradually effect a polishing-of the,surface. The torch :is :moved substantially 4 parallel to the axis ofrotation, as indicated by the dotted lines in Fig. 2, until the entireexterior surface has been repeatedly contacted by the hot flame. Thisoperation may be performed in any suitable manner, such as by hand. Whenthis treatment has been completed, the article is removed from theturntable and again placed on the conveyor as it passes the opening 24.This ware gradually cools as it moves through the section 23 of thelehr, until it reaches a sufficiently low temperature at which time itwill have arrived at the discharge end of the conveyor. The ware canthen be removed and stored or disposed of according to the desires ofthe manufacturer. When certain hollow articles are being treated, it maybe desirable to direct a stream of air into the interior of the warethrough a tube 33. This air is relatively cool with respect to the heatof the torch and prevents the overheating of the ware. It should also beunderstood that if the interior of the article is to be polished, theair may be applied to the exterior of the article 'while the secondaryheat would be applied to the surface being treated. This air, by holdingthe temperature at a predetermined point, prevents the walls of thearticle from losing their stability when subjected to the highertemperature flame employed in polishing the ware. By reason of theintroduction of the cooling air, the temperature of the wall will beconsiderably below the fusing temperature of the material and thestability of the wall will be maintained even though the outer surfacecontacted by the high flame is being fused.

It should be obvious that the ware may be polished on any surface,either inside or out and that any suitable source of heat may beemployed as long as it will quickly raise a localized portion of thesurface to fusing temperature.

From the foregoing, it will be apparent that a new and improved methodof polishing vitreous mate ial has been provided which permits the useof relatively inexpensive materials and such a. rapid production of warethat the latter can be sold at a relatively low cost.-

Due to the rapid rate at which the temperature of the ware is raised inthe actual polishing roperation, only a small amount of material willbefused and the wall which is being polished will maintain its stability.It has been found through actual operation that the finest patterns canbe polished without sacrificing any of the features thereof. One of thedesirable features of the method is that the sharp corners whichcontribute to the beauty of cut glassware will remain after beingpolished.

While the form of embodiment of the present invention as hereindisclosed constitutes a 'pre: ferred form, it is to be understood thatother forms might be adopted, all coming Within the scope of the claimswhich follow.

We claim:

'1. In a method of ornameni ing' thin wall glassware, the stepswhichcomnrise retaining the ware in a heated enclosure until it has beenere-- vated. to predetermined temperature, transferring the ware to arotatable support, rotating the supportat'a predetermined rate of'directe ing heated gases said ware tc maintain the cement clpredetermined temperature, ap-t plying a cone gated stream of heatedgases to a surface of saidware during rotation thereof, the gases" ofsaid stream being of sufficient tensity to fuse the glass at the surfaceof "a 1'0; calized portion, and-moving the concentrated gases to saidware to maintain the same at the temperature of 1000 F., directing aminute stream of heated gases against a surface of said ware duringrotation thereof, the temperature of said gases being sufficiently highto fuse the face of the ware in a direction parallel to the axis ofrotation of the ware, and gradually cooling the ware.

3. Those steps in a method of ornamenting glassware which comprise,retaining the ware in a heated enclosure until it has been elevated to apredetermined temperature, rotating said ware about an axis at apredetermined rate of speed,

directing a heating medium toward said ware,

to maintain said predetermined temperature, directing a cooling mediumover said ware to prevent excessive heating thereof, directing a minutejet of high temperature gas against said ware during rotation thereof,the temperature of said gas being sufliciently high to fuse said glass,and moving said jet of gas over said ware in a direction parallel to theaxis of rotation thereof.

4. Those steps in a method of ornamenting hollow cut glassware whichcomprise, retaining the ware in a heated enclosure until it has beenele:

vated to a predetermined temperature, rotating said ware about an axisat a predetermined rate 'oi speed, directing a heating medium againstsaid ware to maintain said predetermined temperature, directing acooling medium into the interior of said ware to preclude overheatingthereof, applying a minute jet of high temperature gas against theexterior of said ware during rotation thereof, the temperature of saidgas being suflciently high to fuse glass and moving said jet over saidware in a direction parallel to the axis of rotation thereof.

5. The method of fire polishing thin walled cut glassware comprising thesteps of rotating the ware about an axis, holding a torch from which asmall jet of high temperature flame is issuing in close proximity to theware during rotation thereof, and moving the torch in a plane parallelto the axis of rotation of the ware while maintaining the originalspacing between the torch and the ware.

6. A method of fire polishing vitreous ware which comprises rapidlyrotating said ware, simultaneously applying a concentrated source ofheat at a relatively high temperature at substantially a single pointand moving the source of said heat during said rotation constantly alonga glass, moving the minute stream over the surline substantiallyparallel to the axis of rotation.

7. The method of fire polishing thin wall glassware comprising the stepsof rotating the ware about an axis, simultaneously applying a relativelybroad name to heat the ware on one side to a temperature below thefusion point, simultaneously applying a small jet of a concentratedflame of a relatively high temperature well above the temperature of thebroad flame and of a sufficiently high temperature to fuse the glass atthe surface of a localized portion substantially at a single point onthe opposite side of said ware, and simultaneously cooling said ware bydirecting a stream of cooling air into the interior of the ware.

CLARENCE A. BORCHERT. ROBERT H. JOHNSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

